1. Field of the Invention
The present invention relates to position detecting system for specific positions on a minute area such as bonding pad positions on a semiconductor integrated circuit chip.
2. Description of the Prior Art
The bonding process of the semiconductor chip does require very precise detection of a pad position on the semiconductor chip. In general, as shown in FIG. 1, a semiconductor chip 10 is frequently mounted on a mount base 12 or a frame head 14 with a displacement from a given position. An area of a pad 11 of the semiconductor chip 10 connected to a lead 16 made of usually gold is much narrower than each of lead portions 13 on the mount base 12. Therefore, bonding of the lead 16 to the pad 11 requires a higher precision control of the bonding position than bonding of the lead 16 to the lead portion 13. It is for this reason that the edges or the corners of the semiconductor chip 10 are detected without being changed in any way, and using the result of the detection a computer calculates to provide a position of the pad 11, or that a detection mark is marked on the chip 10 and a position of the chip 10 is detected by using the mark. The former method needs a large scale system for the position detection of the chip, and a cracked or chipped edge of the chip 10 often causes a detection error. In the latter method, the mark negatively affects the semiconductor chip 10, often leading to deterioration of the performance. Additionally, the marking cannot uniformly be applied to various types of the semiconductor chips 10. This fact hinders the bonding process of the semiconductor chip 10 from being automated. Further, the marking is not necessarily applied to all types of semiconductor chips. Therefore, it is very difficult to automate the bonding process of the semiconductor chip 10.